The Tracer Development Specialized Resource (Core B) of this P50 grant application provides the contrast agents, quality control and metabolite analysis in humans and animals to assist the individual research and pilot projects. The activities of the Core will consist of eight primary services: 1) to produce the positron emitting radionuclides 18F and 11C;2) to synthesize anW-1-amino-3-[18F]fluorocyclobutyl-1- carboxylic acid (a/itf-[18F]FACBC) for Research Project #1 and Cores A, C and D;3) to synthesize an 18Flabeled CXCR4 antagonist and an 18F-labeled CCR7 antagonist for Research Project #2 and Cores A, C, and D;4) to synthesize amino terminal fragmented-conjugated iron oxide nanoparticles specific for the cell surface receptor of urokinase plasminogen activator (uPAR) for Research Project #3 and Cores A, C, and D;5) The synthesis of MHI-148-AN conjugates for Research Project #4 and Cores A, C, and D;6) to synthesize the tumor targeted 99mTc-ATF peptide by conjugating 99mTc to the amino-terminal peptide fragment (ATF) of the receptor for urokinase plasminogen activator (uPA) for Pilot Project #1 and Cores A, and D;7) to synthesize 11C-labeled PK11195 and the %-labeled PK11195 antagonist, 1-(2-iodophenyl)-Nmethyl- N-(3-[18F]fluoropropyl)-3-isoquinolinecarboxamide for Pilot Project #4 and Cores A, C and D;and 8) to assist in the preparation of RDRC, IACUC, IND and IRB protocols for regulatory approval of the use of radioactivity in humans and animals for Research Projects #1, 2, 3, and 4, Cores A, C, and D, and Pilot Projects #1, 3, and 4. In this regard, the Specialized Resource (Core B) component is highly integrative, being utilized by all 4 Research Projects and of the Pilot Projects, and having collaborative interactions with each of the other cores.